Since I am a happy keePassXC user I would definitely donate time/money/both to push a proper release for the store if someone is interested
Microsoft makes no effort to indicate that evidently the buyer must beware entirely, and that appearance in the appstore means absolutely nothing in regards to it being spam, spyware, or legally 'counterfeit'. This is likely legally speaking risky - they're selling illegal goods, assuming this is a copyright violation which it probably is. Microsoft is guilty of the crime of fencing by doing this. I know that in The Netherlands, that crime (in dutch, 'heling') is a criminal offense. You need to be doing it intentionally, but given that they have now been notified, give it a few days and I'm pretty sure you really could just get em criminally sanctioned.
"Oh but I did not know" as a defense only gets you so far in court. It should get you absolutely nowhere in the court of public opinion, especially given that microsoft is marketing their app store as the opposite.
Apple and google are also guilty of this stuff; wanting all the cash and harping on and on about how much value they add by being the guardian of it all, and then doing an epically horrible job on guarding it.
It's so depressing that the obvious problem (the operators of these app stores are natural monopolists within that context - and monopolists tend not to focus on actually doing a good job because no competition) and that it then almost immediately goes that badly.